SpringBoot Kotlin RestController Test

Consider a controller built using RestController,

package starter.main.content
 
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController
 
@RestController
class StarterController {
 
    @GetMapping("/")
    fun sayHello(): String {
        return "Hello"
    }
}

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Testing with @SpringBootTest & TestRestTemplate §

@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.RANDOM_PORT)  
class IntegrationTest(@Autowired val testRestTemplate: TestRestTemplate) {  
    @Test  
    fun shouldReturnHello() {  
        val response = testRestTemplate.getForEntity<String>("/")  
  
        assertEquals(HttpStatus.OK, response.statusCode)  
        assertEquals("hello", response.body)  
    }  
}

Warning

TestRestTemplate is only auto-configured when @SpringBootTest has been configured with a webEnvironment, meaning it starts the web container and listens for HTTP requests.

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Testing with @SpringBootTest & MockMvc §

@SpringBootTest  
@AutoConfigureMockMvc  
class IntegrationTest(@Autowired val mockMvc: MockMvc) {    
    @Test  
    fun shouldReturnHello() {  
        this.mockMvc.perform(MockMvcRequestBuilders.get("/"))  
            .andDo(print())  
            .andExpect(status().isOk)  
            .andExpect(content().string("hello"))  
    }  
}

@AutoConfigureMockMvc is essential

AutoConfigureMockMvc creates a MockMvc instance and injects it into the test class constructor

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Testing with @WebMvcTest & MockMvc §

@WebMvcTest(StarterController::class)  
class IntegrationTest(@Autowired val mockMvc: MockMvc) {    
    @Test  
    fun shouldReturnHello() {  
  
        this.mockMvc.perform(MockMvcRequestBuilders.get("/"))  
            .andDo(print())  
            .andExpect(status().isOk)  
            .andExpect(content().string("hello"))  
    }  
}

Supply class(es) to @WebMvcTest

• WebMvcTest was introduced because @SpringBootTest is slow as it loads the entire application context before testing, without passing any classes, @WebMvcTest does the same!
• When you do supply a class, only the beans needed for it are loaded

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Related §

• SpringBootTest vs WebMvcTest
• Integration Testing RestController that calls a Service in SpringBoot Kotlin
• Unit Testing RestController that calls a Service in SpringBoot Kotlin

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Refs §

1. https://gustavopeiretti.com/spring-boot-unit-test-rest-controller/
2. https://stackoverflow.com/questions/39213531/spring-boot-test-unable-to-inject-testresttemplate-and-mockmvc